docs: update native recovery code flow docs

[HerrSpeck]

I added more detailed information about the configuration required to get the native recovery code flow to work. Without a new feature flag, you will run into a "422 Browser location change required" error on your device. That means you won't be able to continue with the settings flow after the recovery flow was completed successfully, because native apps do not support browser redirects.

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• I have referenced an issue containing the design document if my change
  introduces a new feature.
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• I have added tests that prove my fix is effective or that my feature
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.12%. Comparing base (0b32ce1) to head (6b640a7).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3806   +/-   ##
=======================================
  Coverage   78.12%   78.12%           
=======================================
  Files         350      349    -1     
  Lines       24146    24124   -22     
=======================================
- Hits        18864    18848   -16     
+ Misses       3862     3855    -7     
- Partials     1420     1421    +1     

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[WoodyWoodsta]

Are there any further details around use_continue_with_transitions feature flag? Does it affect any other flows, and are there any security considerations that we need to know about when enabling this? Is security reduced?